Messed up and put in regular gas
Thread Starter
3rd Gear
Joined: Sep 2025
Posts: 3
Likes: 2
Messed up and put in regular gas
I had over a half a tank of premium and filled it up at a different Chevron and chose regular by accident. Any thoughts on how to proceed? Should I add some Octane boost or just drive it and keep topping off after a quarter tank is gone?
thanks
thanks
Last edited by ATXKnights; May 26, 2026 at 05:04 PM.
Racer
Joined: Dec 2004
Posts: 443
Likes: 311
From: Wayland, MA
My opinion only--The ECU will retard timing so there will be no knock. Gas mileage will suffer 2-4%. I would not drive aggressively but around and about use most of the gas up and then fill with super.
Drifting
Joined: Jul 2008
Posts: 1,792
Likes: 439
From: FEMA Region 4
I think your idea of adding an octane booster would be what I’d do. If premium is 93 where you are and you add a half tank of 87, you’re only down to about 90 octane, which is only 1 point under areas that have 91 octane. You’re probably ok either way
Le Mans Master
Joined: Mar 2001
Posts: 8,456
Likes: 3,948
From: Omaha
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
Don't use octane booster, the owner's manual specifically prohibits doing so (i.e. could void warranty). And yes, there will be visible proof as it leaves a colored tint on plugs and other combustion chamber internals. As others have stated, it'll adjust just fine as you're probably about 90 octane. Even if you filled the entire tank with 87, it would still run fine as the computer will pull timing to protect it. If you want to be extra safe, top off with 93 as soon as you use about 1/4 tank.
Race Director
Joined: Feb 2011
Posts: 14,724
Likes: 5,601
From: AZ
If it was half 93 and you added 87, just don't go full throttle. If it was 91 and you added 87, I would suggest keeping it at modest throttle and under 3K RPM until you are able to get more 91 in it. Maybe there is somewhere near where you are (racetrack maybe) that has 100 octane unleaded and you could add that in when you have 3/4 full, then you would be good to go normally. As indicated above the OM says no octane boosting additives and having used some on my modded no cats LS7 C6Z, they do leave an orange residue on the spark plugs.
Burning Brakes
Joined: Jan 2011
Posts: 988
Likes: 251
From: San Jose CA
You are fine. The performance will be a little less, but the ECU can adjust , especially for just 1 tank.
Just be glad you didn't accidentally fill up w/ diesel, that would be something else entirely
Just be glad you didn't accidentally fill up w/ diesel, that would be something else entirely
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Racer
Joined: Apr 2018
Posts: 475
Likes: 218
I wouldn’t worry about it. I would just not run it too hard until you can refill with premium to avoid knocking. Although a lot of cars say premium is recommended/ required manufacturers know that people will ignore it so they have built in safety guards. You may experience less the peak performance or knock but the engine will be fine.
Race Director
Joined: Jul 2007
Posts: 10,698
Likes: 1,134
I believe in the Beer Fairy
First world problems...it does not matter...it won't hurt the car...no matter what the stickers say. lol...I figured this was just like the humorous threads like the oh no, I left my car in the rain threads...
Last edited by Garret; Yesterday at 09:53 AM.
Le Mans Master
Joined: Mar 2001
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From: Omaha
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
Drifting
Joined: Jul 2005
Posts: 1,323
Likes: 439
From: Tucson Arizona
[QUOTE I'm lucky if a full tank lasts me 250 miles![/QUOTE]
I would be so excited to get 250 a tank lol... I'm happy when I fill up and I break 200 miles of range
I would be so excited to get 250 a tank lol... I'm happy when I fill up and I break 200 miles of range
Last edited by chevyvette1; Yesterday at 01:18 PM.
Advanced
Joined: Oct 2024
Posts: 72
Likes: 61
I would be so excited to get 250 a tank lol... I'm happy when I fill up and I break 200 miles of range [/QUOTE]
If you bought the ZO6 with concerns of gas mileage……..you drove past the Toyota dealership and forgot your Prius there.
LOL
OP. I would drive it easy until it hits 1/4. Then fill it up with 93. Finish that tank easy. Then resume regular warp speed operations!
[/QUOTE]If you bought the ZO6 with concerns of gas mileage……..you drove past the Toyota dealership and forgot your Prius there.
LOL
OP. I would drive it easy until it hits 1/4. Then fill it up with 93. Finish that tank easy. Then resume regular warp speed operations!
Professional Beginner
Joined: Apr 2026
Posts: 37
Likes: 16
From: NC
I have owned high performance cars for many many years. YES, a few are tuned specifically for 93 and some higher...but they are mechanically sound without. yes, as noted, performance level may decrease, but, it will be fine.
Now, this is coming from the guy who will not fill up at a shady, tobacco shop style, dimly lit store, surround by iron bars that sells fire wood, cheeseburgers, puppies, and gas.
Intermediate
Joined: May 2018
Posts: 26
Likes: 9
From: Ocean City MD
Hate to say it, but I did the same thing about a year ago on my '24 Z. Ran it down to1/2 a couple of times didn't run hard. Never a problem and today I can't tell I ever messed up. Enjoy and don't worry.